Information is often written down and communicated by means of pen and paper. Such paper-based information is, however, difficult to manage and communicate efficiently.
Computers are used to an increasing extent for managing and communicating information. The information is entered by means of a keyboard and stored in the computer's memory, for example on a hard disk. The entry of the information by means of the keyboard is, however, slow and it is easy to make mistakes. Nor is it particularly convenient to read large amounts of text on a computer screen. Graphical information, such as drawings or images, is often entered by means of a separate image reader, such as a scanner or the like, in a procedure which is time-consuming, cumbersome, and as often as not gives unsatisfactory results. However, once the information is in the computer, it is easy to communicate it to others, for example as an e-mail or SMS via an Internet connection or as a fax via a fax modem.
In Applicant's Patent Application PCT/SE00/01895, which claims priority from Swedish Patent Application No. 990354-2, filed on Oct. 1, 1999, and which is incorporated herein by reference, a system is described where a pen and paper are used to write down information in the traditional way, at the same time a digital graph being created consisting of several tracks or lines of the movement of the pen across the paper, which graph can be transmitted to a computer. Such a system combines the advantages of management with pen and paper, which many users are used to, with the computer's superior ability to communicate and store information. The sheet of paper is provided with a coding pattern, for example consisting of points or other symbols. The pen has a sensor, preferably optical, which records the coding pattern and, by means of a mathematical algorithm, calculates the position of the pen on the coding pattern.
In this way the traditional pen becomes an excellent input device for the computer, and the computer can be used to store the recorded information instead of the sheet of paper having to be archived in a file. In addition, the information can easily be communicated by means of the computer.
The recorded information contains parts which can be used for different purposes.                1) The digital graph contains an image, such as figures or interrelated lines, which can be interpreted by people, for example letters, a symbol, a figure or a drawing. This is the actual message which was written down and which the user wants to manage in some way, for example to archive or to send to a recipient. This information, so-called message information, is stored in some graphical format, for example a vector format or as a collection of pixels.        2) The part of the message information which consists of letters (handwritten) can be subjected to subsequent processing in the form of OCR interpretation (Optical Character Recognition) or ICR interpretation (Intelligent Character Recognition) for conversion into a character format which can be used by the computer, for example for searching purposes or for cataloguing. Symbols can also be interpreted, for example stenography symbols or icons, to which the user predefines a particular meaning. In the following, this information is called character information.        3) The information can also contain an identification of which pen was used to write down the information.        4) Finally, the graph contains information about where on the surface the graph was written down, so-called absolute position information.        5) In addition, a hard copy of the recorded information can be obtained, if the pen makes physical marks on the sheet of paper.        
Prior-art technique comprises other systems for obtaining absolute or relative position information when writing on a surface. However, these previously known systems only describe the use of such information in order to create message information and/or character information, that is information belonging to the groups 1) and 2) above. Such prior-art technique includes, for example, optical detection of a position-coding pattern on a base according to U.S. Pat. Nos. 5,051,736, 5,442,147, 5,852,434, 5,652,412 and EP-B-0 615 209. Position information can also, as also described in EP-B-0 615 209, be obtained by means of acceleration sensors, or by means of inductive/capacitive/magnetic sensors. Other alternatives are a base incorporating pressure sensors, as described in U.S. Pat. No. 5,790,105, triangulation of signals (light, sound, infrared radiation, etc.) with the use of a plurality of transmitters/receivers, as described in U.S. Pat. No. 5,012,049, or mechanical detection of movement relative to a surface, as described in U.S. Pat. No. 4,495,646. Position information can also be obtained by combinations of techniques. For example, a system is described in WO 00/31682 with combined optical detection of symbols, for determination of absolute position information at low resolution, and acceleration sensors, for the determination of relative position information at high resolution.
Although, according to known prior art, there are several different techniques for recording message and/or character information as described above, there is no system for enabling the user to manage this information in a simple, flexible and structured way.
Known systems for managing information, such as the database system as described in U.S. Pat. No. 5,842,196, comprise as a rule a central server unit and user units in the form of personal computers or terminals, which communicate with the server unit. The server unit contains a database with information stored in data records. Searching these data records and updating the same with new information are time-consuming operations which should be made as efficient as possible. For this reason the data-base is often organized in a tree structure, in which the data records, or data fields in these, are given search indices or key values. It is, however, unclear how this type of database system could be combined successfully with the techniques for recording message and/or character information described above.
U.S. Pat. No. 5,932,863 describes a technique for improving the user interface to electronic media. Paper products are provided with a machine-readable symbol, which is allocated a pre-programmed command in a computer. When a user inputs in the symbol by means of a hand-held scanner, this is transmitted to the computer, where the pre-programmed command is executed, for example to cause the computer to retrieve interactive software from a central data bank and to execute this in the computer. Also in this case, it is unclear how this type of user interface could be combined with the above techniques for recording message and/or character information.